Process for producing purified natural gas from natural gas comprising water and carbon dioxide

Abstract

The invention provides a process for producing purified natural gas from feed natural gas comprising water and carbon dioxide, the process comprising the steps of: (a) removing water from the feed natural gas to obtain natural gas depleted in water and comprising carbon dioxide; (b) contacting the natural gas obtained in step (a) with solid sorbent comprising a metal organic framework to remove at least part of the carbon dioxide, thereby obtaining the purified natural gas.

What is claimed is: 
     
       1. A process for producing purified natural gas from feed natural gas comprising from 50 ppmv to 2 v/v % water, from 1 ppmv to 20 vol % hydrogen sulphide, and from 1 ppmv to 40 vol % carbon dioxide, wherein the process comprises the steps of:
 (a) removing from 80 to 100% of said water from the feed natural gas to obtain natural gas depleted in water to a water content of less than 50 ppmv and comprising carbon dioxide; 
 (b) contacting the water-depleted natural gas obtained in step (a) with solid sorbent comprising a metal organic framework to remove at least part of the carbon dioxide, thereby obtaining the purified natural gas. 
 
     
     
       2. A process according to  claim 1 , wherein the feed natural gas further comprises from 0.1 to 10 vol % hydrogen sulphide. 
     
     
       3. A process according to  claim 2 , wherein in step (a) from 90 to 100% of the water is removed by contacting the feed natural gas with a zeolite molecular sieve. 
     
     
       4. A process according to  claim 3 , wherein the metal organic framework comprises at least one metal ion and at least one bidentate organic compound, wherein the bidentate organic compound is bound to the metal ion. 
     
     
       5. A process according to  claim 4 , wherein the metal ion is Zn 2+  and the bidentate organic compound is terephtalic acid. 
     
     
       6. A process according to  claim 5 , wherein the metal organic framework has a BET specific surface area of at least 500 m 2 /g. 
     
     
       7. A process according to  claim 6 , wherein the partial pressure of carbon dioxide in the feed natural gas is in the range of from 0.1 to 30 bar. 
     
     
       8. A process according to  claim 7 , wherein in step (b) metal organic framework sorbent material comprising hydrogen sulphide and/or carbon dioxide is obtained and the process further comprises the step of:
 (c) regenerating metal organic framework sorbent material comprising hydrogen sulphide and/or carbon dioxide by contacting said sorbent material with a stripping gas at conditions such that hydrogen sulphide and/or carbon dioxide are transferred from the sorbent material to the stripping gas to obtain regenerated sorbent material and a gas stream enriched in hydrogen sulphide and/or carbon dioxide, wherein step (c) is performed either at a lower pressure than step (b) or at a higher temperature than step (b). 
 
     
     
       9. A process according to  claim 8 , wherein the purified natural gas is cooled to form liquefied natural gas. 
     
     
       10. A process according to  claim 1 , wherein both steps (a) and (b) are performed in a single unit. 
     
     
       11. A process for producing purified natural gas from a feed natural gas comprising water and carbon dioxide, the process comprising the steps of:
 (a) removing from 80 to 100% of the water from the feed natural gas by contacting the feed natural gas with a zeolite molecular sieve having an average opening (pore diameter) of 5 Å or less to obtain natural gas depleted in water to a water content less than 50 ppmv and comprising carbon dioxide; 
 (b) contacting the water-depleted natural gas obtained in step (a) with a solid sorbent comprising a metal organic framework to remove at least part of the carbon dioxide, thereby obtaining the purified natural gas, wherein the metal organic framework comprises a Zn 2+  metal ion and a bidentate organic compound. 
 
     
     
       12. A process according to  claim 11 , wherein the feed natural gas further comprises hydrogen sulphide, and from 90 to 100% of the water is removed from the feed natural gas prior to step (b). 
     
     
       13. A process according to  claim 11 , wherein the bidentate organic compound is terephtalic acid. 
     
     
       14. A process according to  claim 13 , wherein the metal organic framework has a BET specific surface area of at least 500 m 2 /g. 
     
     
       15. A process according to  claim 14 , wherein the partial pressure of carbon dioxide in the feed natural gas is in the range of from 0.1 to 30 bar. 
     
     
       16. A process according to  claim 15 , wherein the process further comprises the step of:
 (c) regenerating the solid sorbent obtained from contacting step (b) by contacting said solid sorbent with a stripping gas at conditions such that hydrogen sulphide and/or carbon dioxide are transferred from the sorbent to the stripping gas to obtain regenerated sorbent material and a gas stream enriched in hydrogen sulphide and/or carbon dioxide, wherein step (c) is performed either at a lower pressure than step (b) or at a higher temperature than step (b). 
 
     
     
       17. A process according to  claim 16 , wherein the purified natural gas is cooled to form liquefied natural gas.